This invention relates to a through or window type of current transformer and more particularly to an improved detachable adaptor arrangement for mounting and securing such transformers on a bar primary conductor in a predetermined indexed position.
As is known, the through or window type of current transformers include only a secondary winding wound on a magnetic core through which a bus, transformer terminal or other primary conductor may be passed to serve as the primary winding. The output of the secondary winding of the current tranformer is used for measuring primary current at predetermined and proportionally reduced values provided by the current transformer ratio values. Since the primary conductors received by the current transformers may have different shapes, the current transformers must be adapted for different mountings when receiving the different shaped conductors. However, one extensive use of the current transformers is on rectangular bus bars or spade terminals extending from insulating bushings of high voltage distribution transformers.
Auxiliary bus bar adaptors are known and in one example the adaptor is cemented or bonded within the window opening of a current transformer for adapting it for mounting on spade terminals or other rectangular bar conductors. An adaptor of the aforementioned type is disclosed in U.S. Pat. No. 3,582,852 wherein the described adaptor is not intended to be both removable and reattachable to the transformer. A detachable type of auxiliary adaptor is disclosed in U.S. Pat. No. 3,742,410, assigned to the assignee of this invention. The detachable adaptor includes metal clips for resiliently engaging the opposite outer sides of the transformer. The clips are each separately formed and then the body of the adaptor is molded around the clips so as to form a bar receiving groove for mounting the transformer. While the aforementioned types of adaptors are suitable in many transformer mounting applications, they do not afford a separately attachable adaptor arrangement that is economically manufactured entirely of an insulating material and is attachable to the transformers in a predetermined indexed orientation.